Climate Change Impacts on Valley Carpenter Bees

While our unseasonably warm January/February weather was enjoyable for us humans, it challenges normal life cycles for some of our native California insects. 

mourning cloak butterfly

The warm weather convinced many butterfly and bee species that spring had arrived. Then, just as suddenly, winter returned with cold damp days challenging their survival. Typically insects overwinter in one developmental stage. Some butterflies like the monarch and the mourning cloak overwinter as adults, while others overwinter as a chrysalis waiting for spring to metamorphose into an adult. Preying mantises overwinter as eggs.

The female Valley carpenter bee (Xylocopa varipuncta) overwinters as an adult, her male counterpart does not survive the winter. When the female emerges from a winter torpor in the spring, she starts laying eggs to start a new generation. It takes 40-45 days for the young bees to mature from egg, to larva and then emerge as adults. 

In early January I was surprised to see a female Valley carpenter bee active and stashing supplies in a carved-out wooden den. Now in the last few days, these young Valley carpenter bees have begun to emerge. Unfortunately, instead of the warm spring weather they were expecting to find they have emerged into crisp winter days with cold nights. 

Tuesday evening walking home from voting, I found this newly emerged female Valley carpenter bee listless on the sidewalk. She was cold and appeared thin.

She was just able to cling to a stick that I used to pick her up. I found some native ceanothus flowers and other blooms that I have seen Valley carpenter bees frequent. I put the flowers with the bee in a bug box. We kept her in the house over night.

female Valley carpenter bee with a dusting of pollen

In the morning I was afraid she had not survived the night, but she showed a bit of movement. We opened the box and put her out in the sun in the yard adjacent to flowering plants. By mid-morning she had warmed up and flown off.

The weather is warming again. I hope she survives to pollinate the spring flowers and raise a family of her own. When thousands of years of evolution have timed your entrance into the world to coincide with specific weather and blooming plants, small changes in that series of events can challenge your survival. These are the small impacts of climate change that many of us do not notice, but which will eventually add up to large change.

Hummingbirds challenged by weather changes.
Climate changes to native plants and the animals that depend on them.
Alaskan glacier melting

Video of busy Valley carpenter bees on The Earth Minute.
 Compare them to European honey bees.

Subtle Impacts of Drought & Climate Change in Southern California

It's 66˚F outside at 2:30 pm on a January day. The sky is clear, the day is beautiful. Our mid-winter in southern California is mild and lovely.

Unfortunately, people have difficulty seeing incremental local climate changes if those changes do not have a concrete negative impact on themselves. In addition, most people who have relocated to Los Angeles from places with snowy or harsh winters do not even notice our subtle seasons.

toyon berries, 1/15/15

Today however I came face-to-face with an impact from drought and climate change that is having a direct impact on my neighbors and their migratory relatives. The toyon or California holly should be filled with red berries (what toyon should look like in December/January). Because of the drought the two bushes in the front of the house did not fruit at all this year and the toyon at the top of the hill has fruit that look like this...small and unripe.

The northern mockingbird that only occasionally visits our yard was here this morning hunting for fruit, it found none. The hermit thrush who visits annually was also searching for toyon fruit. Unlike the mockingbird, it has come here from the north to spend the winter in a location that should offer winter fruit. Both are having to supplement their diets with more insects. 

High in the eucalyptus tree the mewing cries of a small flock of cedar waxwings caught my attention. Twenty-seven of these fruit-eating birds sat pondering their next move. They too were here looking for the toyon berries that they expected to find on our hillside. When they found nothing, they went hungry. They regathered and flew on.

For these birds, drought means smaller, less nutritious food. But subtle changes in our climate are also altering when the fruit ripens. Imagine driving across the Mojave desert with the plan to stop at that favorite restaurant only to find that the town is closed up and the next place to find food is 100s of miles away.

Subtle changes in our local climate are impacting wild species that are tied to the fruiting or flowering of specific plants. We need to increase our awareness. 

Touching Climate Change

Do you question climate change?

In my lifetime I have watched glaciers in Alaska retreat by miles. Check out the video we shot of Mendenhall Glacier in Juneau, Alaska.

I've seen dramatic changes in the breeding of Allen's hummingbirds in my California yard and changes in the migration patterns of native birds that visit. Many of the animals are responding to impacts on native vegetation.

Rainfall in California has declined creating our current drought, but the truth is we haven't had a wet season since 2005. Flood years mixed with low rainfall years are normal for us, but the flood years are disappearing.

Small changes can sneak up on you as you ease into them. But if you are documenting daily events in the natural world, either in data, journal, or photos, the dramatic accumulation of change is undeniable. 

I remember when the Mendenhall Glacier covered most of the rocky outcroppings that are now completely exposed. I remember a 300 foot thickness of ice that nearly hid the top of the waterfall that is now completely free to tumble down a barren rock slope. Watch the video and see the beach beside the churning waterfall. I sat on that beach and cried, because when I was a child that beach was completely covered by a wall of glacial ice.   

Warm Autumn Impacting Tortoise Hibernation

There are signs of autumn all around. The leaves of the peach tree are daily turning red and golden.

The toyon fruit (aka California holly) is turning red and attracting the attention of the hungry hermit thrush.

But the on-again, off-again autumn weather is making someone grumpy. The angle of the sunlight signals autumn–time to hibernate–but the warm days keep tempting the desert tortoise to stay up.

As you can tell from the photo, this guy is not asleep. His son, has gone in for the winter. Typically, the old guy is in by mid-October, but this year he can't seem to commit to hibernation. He comes out, sits in the sun, takes a few bites of food then grumbles back into his den. Today he stuck his head out and immediately turned around.

He wants to be asleep, but the warm weather is confusing. Some of the migrating birds have been off in their annual cycles as well. For this desert tortoise who has been in captivity, since the mid-1970s, fluctuating climate is an irritation, but for desert tortoises in the wild there can be serious consequences. If they miss time hibernation, they can get caught away from a protective den when the weather does turn cold. They could use up food reserves before they hibernate.

They do not digest food well without basking in the sun and having hot temperatures. They need to stop eating and completely digest what is in their stomachs before going into a deep sleep. Undigested food in their system can rot while they are hibernating, causing them problems. When tortoises awaken in the spring they have expectations of flowering plants and new greenery that they depend on to replenish themselves after months of not eating or drinking. Changing climate can impact all of the timing in this delicate dance making survival even more of a challenge for wild tortoises.

This grumpy guy has us as caretakers to make sure he has food and vitamin supplements. Wild desert tortoises are on their own. Tortoises around the world need our help. They are important members of their ecosystems and all too frequently they are taken out of the wild, both to their detriment and that of the other plants and animals that depend on them.

Tortoises in Turkey
I recommend book Life in a Shell

Early Arrival of Winter Birds

It is that time of year when I start to look for the migrant birds that arrive to spend the winter in our garden.

This summer has been gruelingly hot. We have had weeks of temperatures over 100˚F. This week of the Autumnal Equinox we have had two record-setting days of high temperatures.

So this morning when I saw our first Oregon dark-eyed junco of the season, I was especially surprised. September is an early arrival for this species. Typically we see them arrive in October. So I got out my bird journals and put together the graph below. (10.01=Oct. 1 of that year)

data compiled by Keri Dearborn

Indeed this is an early arrival for the juncos and this is the second year in a row that they have arrived early. They are coming from local mountains and northern coasts. 

I compared their arrive dates to the rainfall data and interestingly, the heavy rainfall year correlated with the year they didn't arrive until November. The pattern with early arrival isn't as easy to discern. But one thing is certain, in twelve years of recording these arrival dates, this is the first time we have had consecutive years of early arrival in September. Are they coming for resources? Influenced by temperature? Or have two years of minimal average rainfall pushed them out of the hillsides earlier?

It will be interesting to see if other migrating birds also arrive early. 

Climate Change and Hummingbirds

Again this year Southern California experienced abnormally warm weather in December - January. The Allen’s hummingbirds in our yard set about breeding.

The female who has staked out her territory in the driveway, DR, built a beautiful nest in a native Catalina cherry shrub. DR's territory.  Last year, DR had the earliest successful chick reported to NestWatch in North America. But the consequence of the early nesting was that only one chick survived when winter weather returned.

This year, DR once again responded to early days of warm weather and began nesting. Just a few days after laying her two eggs strong winter winds came up and lasted for several days. She rode out the first day keeping her eggs safe in the nest, but on the second day she must have gone off to get some food and wind tossed one of the precious eggs out and onto the pavement.

The remains of the tiny hummingbird egg were smashed on the driveway.

The next day she was on the nest, but the weather turned and became not only windy but cold. DR abandoned the single egg. After several days it was clear, she had decided to cut her losses and build a new nest in a more protected location.

Unusually warm winter weather patterns convince the female Allen’s hummingbirds that spring has arrived. They begin nesting and for the second year, those early nests are unsuccessful. For the tiny hummingbirds it means reproductive opportunity wasted.

Missing Ladybugs

Ladybugs are insects that even a toddler can identify. Their red and black markings are distinct and their rounded shape appears nonthreatening. As predators of aphids and other garden leaf-eaters, ladybugs have one of the most positive insect profiles. Everyone loves ladybugs.

But across the country native ladybug populations are declining. What is happening to these important and beloved insects? Citizen scientists can play an important role in helping scientists sleuth out this environmental problem.

Go looking for ladybugs or just keep your eyes open and aware during your daily activities. When you see a ladybug, take its picture and report it to the Lost Ladybug Project

I spotted this ladybug on a lavender plant on December 9th. Ladybugs hibernate over the winter as adults and typically they group together in a protected location. One year we cut down a live Christmas tree and brought it into the house only to find that there were about 100 ladybugs hibernating in a clump at the center of the tree. The ladybug I took a photo of was out in the warm winter weather. (Climate Change in California) If it gets caught without a protected place to stay when the temperature turns cooler, as it is expected to do this weekend, will it survive the colder temperatures?


Scientists need your eyes to help solve this mystery of Missing Ladybugs.
Other Citizen Science Projects.

Climate Change in California

I know most people think of Southern California as having year-round warm weather. And while it is true that we don't have snow in the lower elevations, we do actually experience cooler winter temperatures with a winter rainy season.

Over the past few years I have been noting the signs of autumn: leafing out of the wild currants, ripening of the toyon berries. The winter hibernation of the western fence lizards and desert tortoises mark the seasonal change as well. While the tortoises are fast asleep, this morning I saw a young fence lizard out warming itself in the sun.


I've also been recording signs of spring: hummingbird nesting, blooming of the manroot and more.


Last year the Allen's hummingbirds in our yard started to seriously nest in January. The earliest date we have recorded. A lone chick survived from these early nests because winter storms did arrive in early February. Winds tossed youngsters out of nests and sudden cold temperatures overwhelmed young chicks. The one Allen's hummingbird chick was the earliest recorded wild bird hatchling in North America in 2010. 

This year we had some early autumn rains, cold weather and then December has had some record warm days. Last year we recorded the manroot blooming the first week in January. On Sunday, December 12th I took these photos of the manroot not only emerging from the ground, but getting ready to bloom. Will this plant survive to fruit in summer if it emerges so early from the ground?


The male hummingbirds are performing breeding displays. Will we see nesting even earlier this year? If so, will the chicks survive when winter temperatures return?

Early Signs of Spring

This year I was hoping to really do some coverage of the signs of spring here in California. The problem is spring is arriving much earlier than I expected. Though it is only the second week in January, there are already early signs of spring all around the yard. (Past Springs 2008)


The manroot is not only sprouting up out of the ground, it has begun to bloom. Also known as the wild cucumber, the root lies dormant most of the year, but early in spring after a rain and warm days the vine emerges from the ground.

The vine twines away from its source, helping to keep the location of its large root a secret. Typically, seeing the vine emerging mid-February is a surprise. This year the blooms are already opening on January 11.

The manroot isn’t the only early sign of spring. The native coffeeberry is blooming and the French pussy willows are budding. The birds are also responding to the warm days. Yesterday a pair of Bewick’s wrens were checking out one of the bird houses in the yard. Two years ago they successfully raised 4 chicks in this house, but it was April - June.

The Allen’s hummingbirds are also showing signs of early nesting. Females are collecting spider web for building and they are chasing the male. This concerns me greatly. Last year we saw hummingbirds start to build nests on January 12, two weeks earlier than in 2008. Nesting attempts that started prior to mid-February ended in failure. Late January or early February storms destroyed nests and offspring. One of the females that got caught up in this cycle of early nesting and failure did not survive the year herself.



When I looked at my recorded temperatures for January 10 over the last six years, I found that while the temperature highs have gone up, the low temperature has increased as well. Rather than nights that dropped to the 30s and 40s, the nights have been warmer than 50 degrees F. Perhaps this is why the birds are fooled into thinking that the worst of winter is past and spring breeding should commence.

Unfortunately, despite these warm days and evenings it remains highly likely that we will experience a storm or frost before spring actually arrives. All of the plants and animals that have jumped forward will be faced with threatening cold or rain. And if the rain doesn’t come, the drought will worsen. Since the “rainy season” began in October, we have had less than six inches of rain. Connection between rain and migratory birds.

Are you seeing early signs of spring?